1. Field of the Invention
The invention is in the field of bridges for string musical instruments.
2. Description of the Prior Art
The terms "sonic" and "sound" are used herein to mean the complete spectrum of compression wave frequencies including audio frequencies and frequencies above and below the audio range.
It is traditional for string instruments such as guitars to have wooden bridges which are mounted on the face portion of the guitar and coupled to the strings by means of an ivory, bone or plastic saddle. The saddle was utilized as a string contact member since it was much harder than wood and would consequently last longer under string tension.
As is quite apparent in inexpensive guitars, the decay of a note is not uniform, but rather has an undulating or a decreasing and increasing sound pattern, which sometimes will be referred to as "rollover." Rollover is thought to be associated with a feedback between the guitar body and the strings themselves via the bridge and saddle members. In guitars of excellent or outstanding quality, the design improvements such as discretely formed and positioned wood bracings on the inside of the top plate of the guitar have the effect of reducing the rollover to some extent thereby providing a somewhat more uniform sound decay. However, a significant random, uncontrolled, vibratory feedback from the body to the strings still exists, and an undulating sound decay is still present even in the best quality instruments.
The conventional stringed instrument bridge presents an unstable platform for the strings which tends to vibrate with the strings, thereby having a muting effect on the upper partial frequencies, so that the strings may only vibrate in the fundamental and first few harmonics. Thus, the desired full spectrum of overtone frequencies is never produced in the instrument, and the quality of musical sounds produced by the instrument is seriously limited. This also causes an undesirably large proportion of low frequency sonic energy output of the instrument, with consequently generally poor carrying power.
The feedback of a flexural nature which occurs through the bridge of a guitar or other stringed instrument involves an undesired phase modulation which causes a cancellation effect that is detrimental not only to the dynamic amplitude and frequency, but also to the timbre. Timbre is affected in at least two ways: (1) the sine wave component of the sound is distorted, and (2) the formant of the tone is altered periodically during the decay.